1. Field of the Invention
The present invention relates to an apparatus for estimating the lifetime of an industrial thermometer, and more particularly, to a fixed-point cell for connection with thermometer protecting tube and an apparatus for estimating the lifetime of the thermometer using the same, which can detect measurement error of the thermometer using constant-temperature property of a metallic material in an area where two phases or three phases coexist, and determine the replacement time of the thermometer.
2. Background of the Related Art
In general, an industrial thermometer refers to an instrument which is inserted into a thermometer protecting tube and then installed in a power plant, a large-scaled refrigeration system, an LNG storage, a steel foundry, and so on, so as to indicate the temperature of an associated industrial apparatus. Because the industrial apparatus shows its operation state through the temperature indicated to the outside, the thermometer mounted on the associated industrial apparatus must exactly measure and indicate the temperature of the industrial apparatus. However, since the industrial thermometer and the thermometer protecting tube may get a thermal shock by a structure of the industrial apparatus, they cannot exactly measure the temperature of the industrial apparatus due to malfunction of sensor elements. Therefore, the industrial thermometer mounted on the industrial apparatus must be frequently inspected.
In order to inspect the industrial thermometer, a structure on which the industrial thermometer is mounted is removed from the associated industrial apparatus, moved into a laboratory, and inspected in the laboratory. However, the industrial apparatus must be in a non-operation state while the industrial thermometer is inspected. So, there may occur an economical loss since the associated industrial apparatus is in an inactivated state during the inspection of the industrial thermometer. Furthermore, because a manufacturer has a tendency to delay periodical inspection of the industrial thermometer in order not to suffer from a loss generated while the associated industrial apparatus is in a non-operation state, the associated industrial apparatus may produce bad products or inflict an injury on workers who work using the industrial apparatus.